Tropical wood · Southeast Asia and Oceania
Jongkong wood
Jongkong (Dactylocladus stenostachys, family Melastomataceae) is a tropical timber from Southeast Asia and Oceania. Dry, its Janka hardness is 720 lbf (3,203 N), and air-dry it weighs about 34 lb/ft³ (545 kg/m³). The figures are from the USDA Forest Products Laboratory's Tropical Timbers of the World, pp. 607–608.
Other names, by country: Merebong (Sarawak), Sampinur (Indonesia), Medang Tabak (Sabah).
Key numbers
- Janka hardness, dry
- 720 lbf (3,203 N)
- As printed: “Janka side hardness 720 lb at 12% moisture content.”
- Air-dry density
- 34 lb/ft³ (545 kg/m³)
- Basic specific gravity
- 0.42 oven-dry weight, green volume
- As printed: “Basic specific gravity (ovendry weight/green volume) 0.42; air-dry density 34 pcf.”
- Shrinkage, green to 12% moisture content
- 4.1% tangential
- Radial 2.1%
One source: USDA Forest Products Laboratory, Tropical Timbers of the World (Chudnoff, 1979 edition), the only published source read for this wood
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE); crushing strength is compression parallel to the grain. The sheet collects these from published tests: it prints 3 data sets, from different tests and sources, so they can differ widely; all are shown, in the sheet's order, each at the moisture content printed beside it, never restated as 12%.
| Moisture | Bending strength (MOR) | Stiffness (MOE) | Crushing strength |
|---|---|---|---|
| Green | 6,510 psi (45 MPa) | 1.35 million psi (9.3 GPa) | 3,470 psi (24 MPa) |
| 17% MC | 9,150 psi (63 MPa) | 1.56 million psi (10.8 GPa) | 4,730 psi (33 MPa) |
| 12% MC | 13,250 psi (91 MPa) | — | 7,550 psi (52 MPa) |
A dash means the sheet prints no value; none is filled in.
What the data sheet says
- Color, grain and texture
- Heartwood yellowish with a pink tinge when freshly cut turning to a red-brown, usually with white flecks, upon drying and exposure; sapwood not differentiated by color. Texture rather fine and even; grain straight or slightly interlocked; without distinctive odor or taste. Included phloem in radial strands present.
- Working properties
- Very easy to work and dresses to a smooth finish; cuts cleanly across the grain.
- Durability
- Not resistant to attack by decay fungi and vulnerable to termites and other insects.
- Uses
- Form work, general construction, furniture components, plywood, interior millwork, used for shingles when treated.
- Where it grows
- Indonesia and Sarawak-Sabah; found in peat swamp forests.
Quoted from Tropical Timbers of the World, pp. 607–608, a USDA Forest Products Laboratory work in the public domain.
Work it out for your project
- Rank woods for furniture with the species picker
Weigh jongkong against other woods on hardness, weight, movement and color, every figure from the Wood Handbook.